rom/exec/findtask.c

   1 /*
   2     Copyright © 1995-2017, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: Search a task by name.
   6     Lang: english
   7 */
   8
   9 #define DEBUG 0
  10
  11 #include <exec/execbase.h>
  12 #include <aros/libcall.h>
  13 #include <proto/exec.h>
  14
  15 #include "exec_intern.h"
  16 #include "exec_locks.h"
  17
  18 /*****************************************************************************
  19
  20     NAME */
  21
  22         AROS_LH1(struct Task *, FindTask,
  23
  24 /*  SYNOPSIS */
  25         AROS_LHA(CONST_STRPTR, name, A1),
  26
  27 /*  LOCATION */
  28         struct ExecBase *, SysBase, 49, Exec)
  29
  30 /*  FUNCTION
  31         Find a task with a given name or get the address of the current task.
  32         Finding the address of the current task is a very quick function
  33         call, but finding a special task is a very CPU intensive instruction.
  34         Note that generally a task may already be gone when this function
  35         returns.
  36
  37     INPUTS
  38         name - Pointer to name or NULL for current task.
  39
  40     RESULT
  41         Address of task structure found.
  42
  43     NOTES
  44
  45     EXAMPLE
  46
  47     BUGS
  48
  49     SEE ALSO
  50
  51     INTERNALS
  52
  53 ******************************************************************************/
  54 {
  55     AROS_LIBFUNC_INIT
  56
  57 #if defined(__AROSEXEC_SMP__)
  58     spinlock_t *listlock;
  59 #endif
  60     struct Task *ret, *thisTask = GET_THIS_TASK;
  61
  62     /* Quick return for a quick argument */
  63     if (name == NULL)
  64         return thisTask;
  65
  66     /* Always protect task lists */
  67 #if defined(__AROSEXEC_SMP__)
  68     EXEC_LOCK_READ_AND_DISABLE(&PrivExecBase(SysBase)->TaskReadySpinLock);
  69     listlock = &PrivExecBase(SysBase)->TaskReadySpinLock;
  70 #else
  71     Disable();
  72 #endif
  73
  74     /* First look into the ready list. */
  75     ret = (struct Task *)FindName(&SysBase->TaskReady, name);
  76     if (ret == NULL)
  77     {
  78 #if defined(__AROSEXEC_SMP__)
  79         EXEC_UNLOCK_AND_ENABLE(listlock);
  80         EXEC_LOCK_READ_AND_DISABLE(&PrivExecBase(SysBase)->TaskWaitSpinLock);
  81         listlock = &PrivExecBase(SysBase)->TaskWaitSpinLock;
  82 #endif
  83         /* Then into the waiting list. */
  84         ret = (struct Task *)FindName(&SysBase->TaskWait, name);
  85         if (ret == NULL)
  86         {
  87             /*
  88                 Finally test the running task(s). This is mainly of importance on smp systems.
  89             */
  90 #if defined(__AROSEXEC_SMP__)
  91             EXEC_UNLOCK_AND_ENABLE(listlock);
  92             EXEC_LOCK_READ_AND_DISABLE(&PrivExecBase(SysBase)->TaskRunningSpinLock);
  93             listlock = &PrivExecBase(SysBase)->TaskRunningSpinLock;
  94             ret = (struct Task *)FindName(&PrivExecBase(SysBase)->TaskRunning, name);
  95             if (ret == NULL)
  96             {
  97                 EXEC_UNLOCK_AND_ENABLE(listlock);
  98                 EXEC_LOCK_READ_AND_DISABLE(&PrivExecBase(SysBase)->TaskSpinningLock);
  99                 listlock = &PrivExecBase(SysBase)->TaskSpinningLock;
 100                 ret = (struct Task *)FindName(&PrivExecBase(SysBase)->TaskSpinning, name);
 101             }
 102 #else
 103
 104             char *s1;
 105             const char *s2 = name;
 106             s1 = thisTask->tc_Node.ln_Name;
 107             /* Check as long as the names are identical. */
 108             while (*s1++ == *s2)
 109                 /* Terminator found? */
 110                 if (!*s2++)
 111                 {
 112                     /* Got it. */
 113                     ret = thisTask;
 114                     break;
 115                 }
 116 #endif
 117         }
 118     }
 119
 120 #if defined(__AROSEXEC_SMP__)
 121     EXEC_UNLOCK_AND_ENABLE(listlock);
 122 #else
 123     Enable();
 124 #endif
 125
 126     /* Return whatever was found. */
 127     return ret;
 128
 129     AROS_LIBFUNC_EXIT
 130 } /* FindTask */
 131